Pdt

PDT is a unique debulking nonthermal technology with the clever use of a photosensitizing drug and the activating red laser beam. Laser light activates the drug to generate singlet oxygen. Singlet oxygen released locally is highly toxic to the microvasculature of the tumor leading to ischemic necro

FIGURE 22-1. Endoscopic view of a recurrent esophageal adeno- FIGURE 22-2. Endoscopic view of the residual esophageal adenocarcinoma before argon plasma coagulation treatment for palliation. carcinoma after argon plasma coagulation therapy.

sis. There may also be an immunological effect as well as a local apoptotic effect. PDT involves drugs, light sources, and light delivery systems. The light for PDT can be delivered endoluminally by microlens fibers, cylindrical diffusers, or inflatable balloon applicators. Drug and light dosimetry and tissue oxygenation determine the treatment effects. PDT can be employed in curative and palliative management of EC (Figures 22-3 and 22-4) (Lightdale, 2000). A randomized study compared PDT (Photofrin) with Nd:YAG laser for palliation of advanced EC (Lightdale et al, 1995). Improvement in dysphagia was equivalent between the two treatment arms. Objective tumor response was significantly higher with PDT at 1 month (32% versus 20%, p < .05). There was no survival difference between the two treatment arms. In this study, the PDT arm had a better tumor response for certain tumor subtypes, including tumors longer than 10 cm, tumors located within the upper third of the esophagus, and tumors located within the angulated portion of the lower esophagus.

PDT is carried out with greater ease and is associated with fewer acute perforations than Nd:YAG laser therapy. In addition, PDT can be used to obliterate tumor ingrowth associated with the use of endoprostheses, but the experience is limited. The main disadvantages associated with PDT include the high drug and equipment costs, as well as the photosensitivity that occurs from the residual drug in the skin. The one major limitation of PDT is for large tumor masses where the light penetration is limited. A light guide is placed "free hand" in the center of the tumor. For bulky tumors, intratumoral insertion of short diffuser (1 to 2 cm) can lead to more destruction. PDT treatment can be repeated. However, the high cost of repeated drug infusion makes esophageal prostheses a better option. Complications resulting from the use of PDT include esophageal strictures occurring in 10 to 50% of patients, transient fever, and pleural effusion. Fistulas and perforations are rare. M-Tetra (hydroxyphenyl)chlorine (Foscan) is an experimental photosensitizer that provides more destruction but with a higher incidence of bleeding and perforation.

Constipation Prescription

Constipation Prescription

Did you ever think feeling angry and irritable could be a symptom of constipation? A horrible fullness and pressing sharp pains against the bladders can’t help but affect your mood. Sometimes you just want everyone to leave you alone and sleep to escape the pain. It is virtually impossible to be constipated and keep a sunny disposition. Follow the steps in this guide to alleviate constipation and lead a happier healthy life.

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